Cutaneous colonization by Staphylococcus aureus in infancy plays an active role in the development of atopic dermatitis (AD), according to the results of a prospective birth cohort study published in the Journal of Investigative Dermatology.

The study enrolled 149 white infants with and without a family history of atopy between July 2010 and November 2012. Study participants were divided into 2 groups: high-risk (infants with ≥1 first-degree relative with atopy) and low-risk (infants with no family history of atopy). Culture-based analysis was performed via axillary and antecubital fossa skin swabs collected at birth and at 7 time points over the infants’ first 2 years of life.

Of the 149 children assessed, 36 developed AD at a mean age of 9.4 months (range,
10 to 24 months), with a mean SCORAD (SCORing Atopic Dermatitis) index of 20.1 (range, 8.0-35.5). In 56% (20 of 36) of the infants who developed AD, the disease presentation was prior to 6 months of age.


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Cumulative AD incidence during the first 2 years of life was 2.6 times as high in the high-risk vs low-risk arms (31% vs 12%, respectively), with the disease presenting more often in winter than in summer (36% vs 14%, respectively). Although AD risk was about 1.7 times as high in boys as in girls, no association was observed between season of birth and AD risk.

At 3 months of age, S aureus was more prevalent on the skin of infants who developed AD later in life. Compared with age-matched controls, the prevalence of AD was increased on the skin of infants at the time of AD onset, as well as at 2 months prior to disease onset. In addition, at the onset of AD, infants who tested positive for S aureus were younger than their uncolonized counterparts.

The researchers concluded that specific changes in early-life skin colonization by S aureus may contribute to the development of AD in infancy.

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Reference

Meylan P, Lang C, Mermoud S, et al. Skin colonization by Staphylococcus aureus precedes the clinical diagnosis of atopic dermatitis in infancy [published online August 22, 2017]. J Invest Dermatol. doi: 10.1016/j.jid.2017.07.834